Blind rivet setting tools



March 31, 1964 E. E. TSCHANTZ 3,127,045

BLIND RIVET SETTING TOOLS Filed Feb. 28, 1962 3 Sheets-Sheet 1 #J Rfi $1 2 Invenfor faumrd E Tsahantz By his Attorney March 31, 1964 E. E. TS'CHANTZ 3,

BLIND RIVET SETTING TOOLS Filed Feb. 28, 1962 s Sheets-Sheet 2 z 10 30 38 1% 2 M Z5 j az l// //l ///I WIIIIIII .83. A IIIIIIIIIIIIIIIA March 31, 1964 E. E. TSCHANTZ 3,127,045

BLIND RIVET SETTING TOOLS Filed Feb. 28, 1962 3 Sheets-Sheet a United States Patent Ofiice 3,127,945 Patented Mar. 31, 1964 3,127,045 BLIND RIVET SETTING T0015 Edward E. Tschantz, Woodbridge, Conn, assignor to United Shoe Machinery Corporation, Boston, Mass., a corporation of New Jersey Filed Feb. 28, 1962, Ser. No. 176,314 8 Claims. (Cl. 218-42) This invention relates to trigger controlled portable power operated tools for setting blind rivets. In more particular, it relates to new and improved power drive connections, between the rivet setting mechanism of the tool and a continuously running electrical rotary motor for actuating said mechanism, to provide one single rivet setting stroke each time the trigger control is manually operated.

The tool of this invention is particularly adapted for the setting of blind rivet assemblies of the type wherein the rivet barrel is set in a work piece by the tensioning of a mandril stem having an enlarged rivet setting head engageable with the blind end of the rivet barrel. Further, this tool can be effectively employed for the tensioning of a mandril in a rivet assembly similar to that disclosed in United States Letters Patent No. 2,533,448, issued December 12, 1950 in the names of A. W. Forman et al.; wherein upon completion of the rivet setting operation, the mandril stem is designed to sever or break as a result of the tensioning stress applied by the setting tool.

An object of this invention is to provide power operated retractable means for engaging and pulling the mandril stern until the rivet is set and the resultant tensioning of the mandril causes the stem of the mandril to become severed from the set rivet assembly.

Another object is to provide a power operated drive for the retractable means, which drive is derived from a rotary electric motor, the drive shaft of which may be engaged through a clutch to provide power for a single retractive stroke of the mandril pulling means.

A further object is to provide automatic means for disengaging the clutch to disconnect the retractable means from the power operated drive after the mandril stem has been severed by a single retractive stroke.

Another object is to provide means, independent of the power operated drive, for returning the mandril gripping and tensioning means to their original forwardly extended position, after the clutch has been disengaged.

Still another of this invention is to provide means for locking the clutch in its disengaged position, so that the continuously running electric motor will not cause a recycling of the tool until the trigger has been again depressed to permit the re-engagement of the clutch.

The above and other objects of this invention will now be described in detail with reference to the accompanying drawings in which,

FIG. 1 is a side elevation partially broken away illustrating a rivet setting tool constructed in accordance with this invention, and as seen with the operating parts in the normal at rest position whereat the gripping and tensioning means are extended forwardly;

FIG. 2 is a sectional view of the pulling head nose piece of the tool, with the parts in the forwardly extended position preparatory to the gripping and tensioning of a rivet;

FIG. 3 is a sectional view illustrating the power operated parts in their at rest position and showing the clutch located in its disengaged position;

FIG. 4 is a view similar to that of FIG. 3, but showing the clutch engaged and the operating parts as seen toward the end of their retractive movement just prior to the severance of the mandril stem;

FIG. 5 is a sectional view of the forward part of the nosepiece, illustrating the retraction of the mandril gripping means just prior to the severance of the mandril;

FIG. 6 is a sectional view showing the power operated parts after the severance of the mandril, with the clutch locked in disengagement and the parts moving toward the extended at rest position of FIG. 3;

FIG. 7 is similar to that of FIG. 5 but illustrating the parts after the severance of the mandril and during their return to the forwardly extending position;

FIG. 8 is an enlarged view, partially in section, showing details of parts as viewed along the line VIIIV]1I of FIG. 3 looking in the direction of the arrows; and

FIG. 9 is an enlarged sectional view of the parts as viewed along the section line IXIX of FIG. 3.

Referring to the drawings and in particular to FIG. 1, the rivet pulling tool therein illustrated is provided with a rivet engaging pulling head assembly, indicated in general by the arrow 10; a central body portion 12, within which is housed mechanism for converting a rotary power driving movement to a reciprocative linear motion; an electric motor, designated in general by the arrow 14, and having a rotary driving shaft; and a handle portion 16, containing a clutch operating trigger 18 and a motor switch operating trigger 2%. It is to be understood that in the normal intended use of this tool the motor remains in continuous operation, excepting when it is desired to lay the tool aside for an extended period; therefore, the electric switch operating trigger 25B is of the type having a latching button 22, which, when pressed, will hold the trigger in engagement with the switch to close the electric circuit until the button is unlatched by manual pressure on the trigger.

In FIG. 2 there are shown two work pieces, W and W each having a drilled opening into which a rivet barrel to be set has been inserted. The mandril portion M of the rivet assembly is then inserted into the nosepiece of the pulling head assembly 10 until the anvil throat 24 of the nosepiece is in firm contact with the flanged end of the rivet barrel. The pulling head 10 is of a wellknown type and is constructed similar to, and operates in the same manner as, the mandril gripping tubular nosepiece illustrated and described in United States Letters Patent No. 2,845,197, issued July 29, 1958 in the name of Charles Newstead. Since the construction of the pulling head It) does not constitute any novel feature of the present invention, and since said patent may be referred to for a detailed disclosure, the following brief description will suffice to explain the cooperative interrelation of the pulling head with the rest of the tool. The pulling head N is of a hollow tubular construction having a jaw case 26 slidably mounted for axial reciprocation within the forward end of the tubular bore 27. A pair of toothed jaw members 28 are cooperatively arranged within the jaw case 26, so that forward pressure of the jaws against the inner rear end of the anvil throat 24 will force the jaws apart to receive or to release amandril stem. Rearward retractive movement of the jaw case 26 causes the jaws to close to grip and to tension the mandril stem as the jaws are power operated rearwardly by a draw bolt 30 threadedly connecting the jaw case 26 to a power operated plunger 32, FIG. 3, which is slidably journaled through a bushing 34 in a bore 35 extending through a forward extension 36 of the tool frame portion 12. The pulling head assembly 10 has been made so that it may be unscrewed and detached readily from the extension 36, by loosening an adjustment lock nut 38, because a change in the size or type of the rivets to be set may require a corresponding change in the pulling head assembly to be employed.

When the assembly 10 is detached from the rest of the tool, as illustrated in FIG. 2, the jaws 28 are held in their forwardly extended or open position by the force of a compression spring 40 acting between a rearwardly facing shoulder on the bolt 30 and another shoulder toward the rear of the bore 27. Thus, when the power operated portion of the tool is attached to any given pulling head assembly while the tool is in its normal at rest position, the proper adjustable relationship will be maintained in the threaded connections between the draw bolt 30 and the power operated plunger 32 which is formed of two parts telescopically threaded together. The plunger 32, in turn, is constantly urged to its forwardly extended position by the force of a relatively strong compression spring 42 nested between the rear face of a snap ring 44 and a forwardly facing shoulder of the bore 35.

During the power operation of the tool to set a rivet, the linear retractive movement of the plunger 32 against the forwardly directed force of the spring 42 is produced by the rotary movement of a worm wheel 46, which, when a clutch is engaged, is power driven by a worm gear 48. The worm wheel 46 is provided with a series of peripheral teeth 50 and is rotatably mounted in the housing of the body portion 12 by a transverse stud bolt 52 aflixed at both sides to the housing, FIGS. 8 and 9. Each side face of the wheel 46 carries an eccentric or crank 54 and each eccentric is pivotally linked to the rearward portion of the plunger member 32 by a connecting rod 56 having a circular strap end surrounding the eccentric and the other end pivotally fastened tothe rear of the plunger 32 by a transverse pin 58. The degree of eccentricity of the crank members 54 is such as to produce a much greater linear retractive movement of the plunger 32 than would be required to tension a mandril stem beyond its elastic limit and cause the stem to sever. Thus the mandril will be severed and the tensioning load, required to sever the mandril, will always be relieved before the worm wheel 46 has rotated 180 beyond the at rest position of FIGS. 1 and 3. In practice it has been observed that a tool, constructed as herein illustrated, normally will cause the severance of a mandril when the plunger 32 has been retracted to approximately the position depicted in FIG. 4. Therefore, during the remaining retractive movement required to bring the eccentric cranks to their rear dead center position, the only load being imposed upon the power driving mechanism is the force required further to compress the springs 40 and 42. It is to be noted that the force of both of these springs is substantial enough to return the retractable parts of the pulling head assembly to their forward at rest position after the eccentric of the worm Wheel has been power driven past the rear dead center position and after the power driving engagement of the driving clutch member 66 with the worm gear 48 has been terminated in a manner which will be hereinafter fully described.

The power train for rotating the worm wheel 46, in a counterclockwise direction as viewed in FIG. 3, consists of an electric motor drive shaft 68 which is geared, through a speed reduction gear train designated generally by the arrow 62, to drive a power shaft 64 continuonsly whenever the trigger 20 is actuated to close the electric circuit to the motor 14. A driving clutch member 66 is integrally affixed to the forward portion of the shaft 64 and is positively rotated therewith in the direction indicated by the arrow. The worm gear 4-8 is mounted for substantially free rotation upon a medial portion of the power shaft 64, and it is also shiftable axially along the shaft 64 into and out of engagement with the power operated driving clutch member 66. A relatively light compression spring 68 closely fits around a rear portion of the shaft 64 and is nested between a rear shoulder 70 of the shaft and the rear face of the worm gear 48, thus exerting a light forwardly directed pressure tending axially to shift the gear 43 toward and into driving engagement with the clutch member 66. Also, during the rotation of the power shaft 64, the accompanying rotation of the shaft shoulder 79, against which shoulder the rear end of the spring 68 is constantly pressed, tends frictionally to rotate the spring in the direction of the shaft rotation, and this frictional radial force is transmitted through the forward end of the spring 68 to the worm gear 48, which, if unrestrained and free to rotate, would move itself forward along the shaft 64 and into driving engagement with the clutch member 66. However, in the at rest condition of the tool as viewed in FIGS. 1 and 3, the Worm gear 48 is positively locked out of engagement with the driving clutch member by a vertically shiftable detent pin 72 that is normally spring pressed upward to hold the upper end of the pin engaged within a circumferential locking groove 74 formed around the rear hub portion of the worm gear 48. Thus a forward axial shifting movement of the worm gear cannot be effected until the detent pin is withdrawn from the groove 74 by a manual depressing of the trigger 18, FIG. 4. While the detent pin 72 is elevated, thereby to prevent any forward shifting of the worm gear toward the clutch engaging position, the worm gear is also prevented from being rotated by the torsional stress of the spring 68, because the worm gear remains constantly in mesh with the teeth 50 of the worm wheel 46, and this wheel is being held stationary in the position of FIG. 3 by the force of the springs 40 and 42 which have rotated the worm wheel until the eccentrics 54 are in their forward dead center position. With the force of the springs 40 and 42 thus resisting rotation of the worm wheel away from its at rest position of FIG. 3, the Worm gear 48 can be rotated by its spring 68 only after withdrawal of the detent 72, thereby permitting the simultaneous rotary and axial movements of the gear 48 to bring the gear forward on the shaft 64 until it is engaged with the clutch member 66. After the detent pin 72 is withdrawn and the worm gear 48 has shifted into driving engagement with the clutch member 66, FIG. 4, the trigger may be released and the top end of the pin 72 will remain in its withdrawn position because the detent receiving groove 74 is no longer in axial alinement with the end of the pin. Once the foregoing power transmitting engagement of the parts has been established, the Work load, or resistance to the retractive movement of the pulling head assembly, will cause the worm gear 48 to be firmly held in engagement with the driving clutch member 66; and the heavier the work load becomes, the greater the pressure becomes tending to hold the parts in driving engagement. While the gear 48 is not keyed to the power shaft 64, and therefore is only positively driven by the rotation of said shaft when the gear is engaged with the clutch 66, another material force tending to turn the gear 48 in the direction of shaft rotation is the frictional torque between the journaled bearing surface of the gear upon the rotatmg surface of the shaft 64. As will be fully explained hereinafter, this frictional force in the journal bearing does actually rotate the gear after the clutch is dlsengaged and while the force of the springs 40 and 42 are completing the rotation of the worm Wheel 46 to return the tool parts to the extended at rest position of FIG. 3.

With the foregoing constructional features in mind, the following brief description of the operational phases of the tool will readily be understood. Having inserted the blind end of a rivet barrel through the work pieces to be fastened, the operator presents the tool to the work so that the mandril M enters the anvil throat 24 and extends between and beyond the open jaw members 28, FIG. 2. At this time the trigger 20 is latched in depressed position so that the electric motor is driving the power shaft 64 constantly, and the remaining parts of the tool are in the at rest or extended position of FIGS. 1 through 3. To initiate an automatic cycle of the tool to set a rivet, sever the mandril and return the tool parts to their at rest position, the operator depresses the trigger 18, thereby extracting the detent 72 from the worm gear 48. Now the only factor holding the worm gear from axial movement, in response to the thrust of the spring 68, is the meshed relationship of the gear 48 and the teeth 50 of the wheel 46. As already stated, the wheel 46 is being forcefully held against movement by the springs 40 and 42; however, the rotary frictional forces acting upon the worm gear both through the spring 68 and through the journal bearing surfaces, and also the axially directed force of the spring 68, all combine to turn the gear 48 in the direction of shaft rotation. While the teeth 50 of the wheel 46 are held stationary, the turning of the worm gear 43 advances the gear axially of the shaft 64 into engagement with the clutch member 66. Now the worm gear is being positively power driven by the motor, and the worm wheel is caused to rotate, FIG. 4, in a counterclockwise direction to retract the mandril gripping and tensioning mechanism in the pulling head 10. Rearward movement of the jaws 28 causes them to grip the mandril and to apply increasing tension thereto, while at the same time the springs 40 and 42 are being increasingly compressed by the retractive movement of the plunger 32. The force tending to hold the gear 48 engaged with the driving clutch member 66 is intensified as the work load increases, and the trigger 18 now may be released by the operator. Continued retraction of the jaws 28 causes the mandril stem to become severed when the tool parts are approximately in their respective positions as illustrated in FIGS. 4 and 5. If the operator has not already released the trigger 18, he should release it now when he either hears or feels the severance of the mandril stem. Continued rotation of the worm wheel 46 carries the eccentrics 54 past their rear dead center position whereupon the fully compressed springs 40 and 42 tend to drive the worm wheel at a greater rate of speed than that being delivered to the wheel through the clutch engaged worm gear 48. Now the relationships of the driving forces and the load direction, being exerted between the driving clutch member 66, the gear 48 and the wheel '46, are completely reversed, with the result that the wheel 46 forces the gear 48 apart from the clutch member 66. The axial shifting of the worm gear 48, FIG. 6, as a result of the driving force of the springs 40' and 42, continues until the spring pressed detent pin 72 is automatically reinserted in the locking grooves 74 and the spring 68 is recompressed. With the worm gear thus locked out of engagement with the driving clutch member, the worm gear continues to be rotated by the driving forces of the wheel 46 and the frictional torque in the journal bearing of the gear, thereby permitting the continued counterclockwise rotation of the wheel 46, under the urgency of the springs 40 and 4-2, to move the parts from the position illustrated in FIG. 6 to their extended at rest position of FIGS. 1 and 3. It is essential that the motor 14 remain in operation during this period to impart the frictional torque that causes the worm gear 48 to rotate in normal meshed relationship with the teeth 50' of the gear wheel 46 to permit the springs 40 and 42 to return the gear wheel to the original position. After the force of the springs 40 and 42 have restored the parts of the tool to the original position of FIGS. 1 and 3, the rotation of the worm gear will stop even though the power shaft 64- continues to be driven by the motor 14, since the slight frictional torque applied thereto by the shaft 64 is insuflicient to cause any substantial movement of the gear wheel 46 past dead center against the force of springs 40 and 42. The tool, having completed one operative cycle, is now prepared to be engaged with another rivet to be set, and all that is required on the operators part is that the trigger 18 be momentarily depressed until the rivet tensioning work load is again applied to the rotating worm gear 48 in the manner already described.

It will readily be perceived from the foregoing description that the power tool of this invention provides novel and most advantageous means for maintaining the clutch elements in power driving relationship during the entire retractive operating stroke of the tool, and for automatically disengaging said clutch elements prior to the completion of the operative cycle of the tool, whereby a recycling of the tool is effectively prevented.

Whereas the construction of the preferred embodiment of the invention, as illustrated in the drawings and as hereinbefore described, contains a number of refinements of a commercial nature designed to enable the tool parts to be manufactured, assembled and maintained more readily, the hereinafter claimed invention is not to be construed as limited to the particular embodiment as above described, unless the claimed invention is thus limited by specific restrictive language contained in a claim. Accordingly, in constructing the breadth of the claims, it is immaterial that the pulling head has been designed so that it may be detached from the rest of the tool. Also immaterial to the scope of the claimed invention is the fact that in the preferred embodiment the plunger 32 is formed of two members telescopically threaded together within the barrel of the frame extension 36.

It is obvious that a satisfactory operative tool could be constructed in accordance with the present invention if the barrel of the pulling head were directly connected with the body portion 12 of the tool, and if the jaw case 26 were directly connected by a single draw bolt to the power opera-ted pin '53. It is also within the contemplation of this invention that the source of power for driving the motor drive shaft 60 be derived from a rotary pneumatic motor, in which case the trigger 20 would be operatively connected to an air valve for supplying pneumatic pressure to the motor.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l1. A blind rivet setting tool for gripping and tensioning the mandril stem portion of a rivet to set the rivet and to sever the mandril stem, comprising a pulling head provided with a retractable rivet engaging and gripping assembly; resilient means yieldably urging said assembly forwardly into its extended mandril stem receiving position; a crank for retracting said assembly beyond the position whereas the mandril stem becomes severed; a power operated member for thus operating the crank; and a pair of intermeshing gears, one of which is rnovable bodily and rotatively relatively to the other gear to connect said crank and the power operated member.

2. A blind rivet setting tool, as defined in claim 1, wherein said one gear is rotatably journaled on a common shaft with the power operated member and is yieldably urged by a spring for bodily movement in a direction axially of the shaft toward and into operative engagement with the power operated member.

3. A blind rivet setting tool, as defined in claim 2, wherein, after the retractive movement of the assembly, said one gear is automatically moved axially out of operative engagement with the power operated member in response to the continued rotation of the crank by said resilient means.

4. A blind rivet setting tool for gripping and tensioning the mandril stem portion of a rivet to set the rivet and to sever the mandril stern, comprising a pulling head provided with a retractable rivet engaging and gripping assembly; resilient means yieldably urging said assembly forwardly into its extended mandril stern receiving position; a crank for retracting said assembly beyond the position whereas the mandril stem becomes severed; a power operated member for thus operating the crank; and a pair of intermeshing gears, one of which is movable bodily and rotatively relatively to the other gear to connect said crank and the power operated member, and then reversely to disconnect said power operated member 7 and the crank in response to. the action of said resilient means on said assembly.

5. A blind rivet settingtool for gripping and tensioning the mandril stem portion of a rivet to set the rivet and to sever the mandril stem, comprising a pulling head provided with a retractable rivet engaging and gripping assembly; resilient means yieldably urging said assembly forwardly into its extended mandril receiving position; a driven power shaft having a driving clutch member affixed thereto so as to be rotatable therewith; a worm gear journaled on a portion of said shaft adjacent the driving clutch member so as to be axially movable into and out of positive driving engagement with the clutch member and so as to be frictionally rotatable by said shaft when out of driving engagement with said memher; a crank operatively connected between said assembly and a worm wheel, said worm wheel being in mesh with the worm gear for driving the crank to cause said assembly to move rearwardly when the gear is in driving engagement with the clutch member; a spring yieldably urging the gear bodily in an axial direction into driving engagement with said member; a manually releasable detent for holding the gear away from said member; and means responsive to the completion of the retractive movement of the pulling head for moving the worm gear axially out of engagement with the driving member.

6. A power operated blind rivet setting tool having rivet gripping jaws which during the rivet setting stroke of the tool are power retracted against the resilient force of a return spring, comprising a rotatable worm wheel having a crank and eccentric thereon adapted to impart retractive movement to said jaws on rotation of said worm wheel, a worm gear in mesh with the worm wheel, said gear being movable bodily and rotatively relative to said wheel; a power driven member rotating eoaxially with said gear; yieldable means urging the gear bodily into driving engagement with the power driven member for imparting retractive movement to said jaws; and means, including the force of the return spring, operative after completion of the retractive rivet setting stroke for urging the gear bodily out of engagement with the power driven member and into engagement with a manually releasable detent for holding the gear out of engagement with the power driven member.

7. Apower operate-d rivet setting tool having rivet engaging and gripping means reciprocatively mounted for linear movement between a forwardly extended at rest position and a rearwardly retracted position to tension and set a rivet assembly, comprising a resilient return spring exerting a force normally tending to move the gripping means forwardly and to hold said means at the ex- I tended at rest position, and a toothed worm wheel carrying an eccentric operatively linked to the gripping means, whereby the force of the return spring acts upon the worm wheel tending to rotate. the wheel until the eccentric and the gripping means are in their respective forward positions, power operated driving means for rotating the worm wheel in a given direction against the force of said spring to move the eccentric and gripping means to their respective rearward positions; and means responsive to the completion of said rearward movement for disengaging the power drive means, whereby the gripping means may be returned to their at rest position by the force of the return spring;

8. A blind rivet setting tool for gripping and tensioning the mandril stem portion of a rivet to set the rivet and to sever the mandril stem, comprising a pulling head provided with a retractable rivet engaging and gripping assembly, resilient means yieldably urging said assembly forwardly into its extended mandril stem receiving position; a rotatably mounted Worm wheel provided with an eccentric crank operatively connected to said assembly sothat, in each cycle of the tool, the first half rotation of said wheel will retract the assembly rearwardly beyond the position where the mandril stem becomes severed, and the second half rotation will return the assembly to its extended position; a worm gear in mesh with said wheel and freely journaled on a power driven shaft so as to be axially and rotatably movable with respect to said shaft; a, driving clutch member integrally secured to the shaft adjacentone end of the worm gear; a compression spring encircling a portion of the shaft and acting between theopposite end of the worm gear and a shoulder of the shaft, thereby providing both a yieldable force tending to move the gear axially of the shaft into engagement 'with said clutch member and a frictional force tending -to rotate the gear in a direction to advance it axially into engagement with the clutch member; a detent engageable with said gear whenever the gear is axially removed apart from the clutch member to hold the gear thus apart against the forces of said spring; and manually operated means for disengaging the detent to initiate an operative cycle of the tool.

No references cited. 

1. A BLIND RIVET SETTING TOOL FOR GRIPPING AND TENSIONING THE MANDRIL STEM PORTION OF A RIVET TO SET THE RIVET AND TO SEVER THE MANDRIL STEM, COMPRISING A PULLING HEAD PROVIDED WITH A RETRACTABLE RIVET ENGAGING AND GRIPPING ASSEMBLY; RESILIENT MEANS YIELDABLY URGING SAID ASSEMBLY FORWARDLY INTO ITS EXTENDED MANDRIL STEM RECEIVING POSITION; A CRANK FOR RETRACTING SAID ASSEMBLY BEYOND THE POSITION WHEREAS THE MANDRIL STEM BECOMES SEVERED; A POWER OPERATED MEMBER FOR THUS OPERATING THE CRANK; AND A PAIR OF INTERMESHING GEARS, ONE OF WHICH IS MOVABLE BODILY AND ROTATIVELY RELATIVELY TO THE OTHER GEAR TO CONNECT SAID CRANK AND THE POWER OPERATED MEMBER. 